Sheet feed mechanism



19.67' J. R. CASSANO ETAL 3,301,551

SHEET FE'ED MECHANISM FiledDec. 31, 1964 '7 Sheets-Sheet 1 6L5 0 WmiHHHHHHW INVENTORS JAMES R. CASSANO ATTORNEYS Jan. 31, 1967 J. R.CASSANO ETAL SHEET FEED MECHANISM '7 Sheets-Sheet 2 Filed Dec. 51, 1964INYENTORS.

JAMES R. CASSANO B LYMAN H. TU NER- ATTORNEYS Jail- 1967 J R. CASSANOETAL 3,301,551

SHEET FEED MECHANISM Filed Dec. 51, 1964 '7 Sheets-Sheet 4 3gp as: 3527k 353 a 36 555- 111!!! aa/ FIG; 9 i

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INVENTORS. JAMES R. CASSANO LYMAN H. URNER B 1967 J. R. cAssANo ETAL 3,

SHEET FEED MECHANISM '7 Sheets-Sheet 7 Filed Dec. 31, 1964 mmv \mv om mm0 F '3 a w? M m mm m NW km n Wm 1% m .l\\ ow n \vm a? m? NR) mvv kmm a aw .33 f 26 3% o 3.9 E 95 .0 M? Q: w o m% Wa LN? an rL o mun EB mw \G$32% 29 2% HyRNER ATTQRNEYS 3,301,551 SHEET FEED MECHANISM James R.Cassano, Rochester, and Lyman H. Turner,

Pittsford, N.Y., assignors to Xerox Corporation, Rochester, N.Y., acorporation of New York Filed Dec. 31, 1964, Ser. No. 422,692 2 Claims.(Cl. 271-62) This invention relates to improvements in sheet feedingdevices and, particularly, to an improved paper stack advancingmechanism for use in a reproduction machine.

More specifically, the invention relates to an automatic control devicefor maintaining the level of a paper stack in a paper feed mechanism ata predetermined height which will aid in the separation and advancementof a single sheet from that height. In cooperative relationship there isalso provided means for terminating operation of the reproductionmachine when the paper stack has been depleted and for permitting easypositioning of the paper stack holding means to enable an operator toadd more paper to the holding means. For convenience of illustration,the invention is described with reference to its use in conjunction witha paper feeding'mechanism in a Xerogr'aphic machine. However, it is tobe understood that it may be employed with equal facility in otherfields.

It is, therefore, the principal object of this invention to improvepaper stack advancers for a sheet feeding mechanism whereby the topmostsheet is continuously maintained at a predetermined height to permitease of separation of the top sheet at that height.

For a better understanding of the invention, as well as other objectsand further featuresthereof, reference is had to the following detaileddescription of the invention to be read in connection with theaccompanying drawings, wherein: a

FIG. 1 illustrates schematically the preferred embodiment of axerographic reproducing apparatus adapted for automatic operation, andincorporating a paper feed mechanism utilizing a paper stack levelcontrol device constructed in accordance with the invention;

FIG. 2 is a top view of the paper tray and paper feed mechanism;

FIG. 3 is a side sectional view of the paper feed mechanism and thepaper level control mechanism taken along the line 3-3 in FIG. 2, withsome parts removed;

FIG. 4 is a sectional view of the paperregister rollers associated withthe paper feed mechanism;

FIG. 5 is a fragmentary view of a detail in the paper level controlmechanism;

FIG; 6 is a sectional view of the paper feed mechanism taken along theline 6-6 in FIG. 2;

FIGS. 7, 8 and 9 are illustrations of a detail used in separating sheetsfrom a stack of papers, shown in perspective, from the side and the top,respectively;

FIG. 10 is a sectional view of the paper separator roller and theassociated elements;

FIG. 11 is a schematic view of a drive system for use with the paperfeed mechanism; and,

FIG. 12 is an electrical circuit that may be utilized for the operationof the invention.

Although it forms no part of the subject invention, there is shownschematically in FIG. 1 a continuous xerogr'aphic apparatus for thepurpose of illustrating a suitable environment for the paper feedmechanism of the subject invention.

As shown schematically in FIG. 1, the automatic xerographic reproducingapparatus comprises a Xerographic plate 14 including a photoconductivelayer or light-receiving surface on a conductive backing and formed inthe shape of a drum, which is mounted on a shaft journaled in a frame torotate in the direction indicated by the United States Patent 03,301,551 Patented Jan. 31, 1967 arrow to cause the drum surfacesequentially to pass a plurality of xerographic processing stations.

For the purpose of the present disclosure, the several xerographicprocessing stations in the path of movement of the drum surface may bedescribed functionally as follows:

A charging station, at which a uniform electrostatic charge is depositedon the photoconductive layer of the xerographic drum;

An exposure station, at which a light or radiation pattern of copy to bereproduced is projected onto the drum surface to dissipate the drumcharge in the exposed areas thereof and thereby form a latentelectrostatic image of the copy to be reproduced;

A developing station, at which a xerographic developing materialincluding toner particles having an electrostatic charge opposite tothat of the electrostatic latent image are cascaded over the. drumsurface, whereby the toner particles adhere to the electrostatic latentimage to form a xerographic powdered image in the configuration of thecopy being reproduced.

A transfer station, at which the xerographic powder image iselectrostatically transferred from the drum surface to a transfermaterial or support surface; and

A drum cleaning and discharge station, at which the drum surface isbrushed to remove residual toner particles remaining thereon after imagetransfer, and at which the drum surface is exposed to a relativelybright light source to effect substantially complete discharge of anyresidual electrostatic charge remaining thereon.

As shown, the charging arrangement includes a corona charging device 15which includes a corona discharge array of one or more corona dischargeelectrodes that extend transversely across the drum surface and areenergized from a high potential source and are substantially closedwithin a shielding member.

Next subsequent thereto in the path of motion of the xerographic drum isan exposure station. An optical scanning or projection system isprovided to project a flowing image onto the surface of thephotoconductive drum from a moving original.

The optical scanning or projection assembly may comprise a minifielddata card projection system 11 which is adapted to scan individual datacards with a light line and project the image rays onto the movinglight-receiving surface of the xerographic drum. The scanning light maybe provided by a suitable light source arranged to scan a minifield datacard. The data card image rays are directed through a lens 12 onto thexerographic drum through a slot in a fixed light shield 13 positionedadjacent to the xerographic drum surface.

Adjacent to the exposure station is a developing station A in whichthere is positioned a developer apparatus 16 including a casing orhousing having a lower or sump portion for accumulating developermaterial. A bucket type conveyor is used to carry the developingmaterial to the upper part of the developer housing where it is cascadedover a hopper chute onto the xerographic drum to effect development.

Positioned next and adjacent to the developing station is the imagetransfer station B which includes a sheet feeding arrangement adapted tofeed sheets of support material, such as paper or the like, successivelyto the xerographic drum in coordination wtih the presentation of thedeveloped image on the drum surface at the transfer station.

The sheet feeding mechanism includes a sheet feed device 18 adapted tofeed the top sheet, of a stack of sheets on a tray 20, to feed rollerswhich arrests and aligns each individual sheet of material and then intimed relation to the movement of the xerographic drum, advances thesheet material into contact with the xerographic drum in registrationwith a previously formed xerographic powder image on the drum.

The transfer of the xerographic powder image from the drum surface tothe sheets of support material is effected by means of a corona transferdevice 21 that is located at or immediately after the line of contactbetween the support material and the rotating drum. In operation, theelectrostatic field created by the corona transfer device is effectiveto tack the support material electrostatically to the drum surface,whereby the support material moves synchronously with the drum while incontact therewith. Simultaneously with the tacking action, theelectrostatic field is effective to attract the toner particlescomprising the xerographic powder image from the drum surface and causethem to adhere electrostatically to the surface of the support material.

Immediately subsequent to the image transfer station, there ispositioned a stripping apparatus to paper pick-off mechanism 22 forremoving the sheets of support material from the drum surface. Thisdevice may be of the type disclosed in Rutkus et a1. United StatesPatent 3,062,536 for stripping the leading edge of the sheet from thedrum surface and to direct it onto an endless conveyor 24 whereby thesheet material is carried to a fixing device 25.

At the fixing device, the transferred xerographic powder image on thesheet of support material is permanently fixed or fused thereto as byheat. After fusing, the reproduction is discharged from the apparatus ata suitable point for collection externally of the apparatus by means ofthe conveyor 26. In the arrangement shown, the reproductions aredischarged from conveyor 26 into a receiving tray 495.

The next and final station in the device is a drum cleaning station C,having positioned therein a corona preclean device 27 to remove anypowder remaining on the xerographic drum after transfer.

It is believed that the foregoing description is sufficient for thepurposes of this application to show the general operation of axerographic reproducing apparatus using a roller fusing deviceconstructed in accordance with the invention. For further detailsconcerning the specific construction of the xerographic apparatus andthe data card handling apparatus 11, reference is made to copendingapplication Serial No. 422,804, filed concurrently herewith on December31, 1964, in the name of Hewes et a].

Referring now to FIGS. 2-12 of the drawings, there is shown a preferredembodiment of a paper feed mechanism 18 constructed in accordance withthe invention.

The sheet feeding mechanism 18, positioned in the image transfer stationB, for seriatim feeding of cutsheet transfer material into contact withthe xerographic drum so that the developed powder images on the surfaceof the drum may be transferred to the transfer material, consists of atray for holding a supply of cut-sheet trans fer material, separatorrollers and devices for separating a single sheet of transfer materialfrom said supply, feed rollers for feeding a single sheet intoimpression contact with the drum and means for coordinating theoperation of the separator rollers and feed rollers to thereby feed asingle sheet of transfer material into contact with the drum for properregistration of the powder image on the drum onto the transfer material.A paper tray level control device is provided for raising the tray assheets of paper are fed from the top of the paper supply.

The apparatus for feeding sheets of transfer material to the xerographicdrum 14 in timed relation to the appearance of a developed image thereonincludes a pair of register feed rollers 280 and 281, usually made ofrubber or similar material, mounted in cooperative relation to eachother in front of guides 282 and 283 which direct sheets of transfermaterial forwarded by said feed rollers into contact with the drum 14 ata point at or slightly in advance of the corona transfer device 21.

The feed roller 280, which is a driven roller, is mountlateral sections294, 295 and with a left side bent down' ed in position by a shaft SH6journaled in the machine support plates 4 and 5, and is driven by apulley 284 (see FIG. 11) secured to the end of the shaft SH6. The feedroller 281, which is an idler roller, is mounted on a shaft SH19journaled at its ends in arms 285 pivotally mounted on frame plates 4and 5, the feed roller 281 being yieldingly biased against the feedroller 280 by means of springs 286 so that feed roller 281 may be drivenby frictional engagement with roller 280 or with a sheet of transfermaterial interposed between said rollers.

A supply of cut-sheet transfer material 287, that is, typically sheetsof paper or the like, to be fed one at a time to the feed rollers 280and 281, is held in the paper tray 20 slidably positionable from theside of the machine between frame plates 4 and 5. The paper tray 20includes a base comprising three sections: a stationary base member 288,a left-hand angle member 290, and a righthand angle member 291. Theangle members 290, 291 are each formed with upright sheet guide portions292, 293 and later portions 294, 295, respectively, and are positionedwith their guide portions parallel to the sides of the base member 288and with their lateral portions extending in the same plane as thecenter section 296 of the base member 288.

The base members 290 and 291 are actuable toward and away from eachother and the center section 296 by a linkage system mounted below thesection 296. As shown in FIG. 6, the base member 288 is formed with thecenter section 296 coplanar with the left and right portion 297 and aright side bent down portion 298. The portions 297, 298 are coplanar andare located immediately below the sections 294, 295, respectively, andupon which these sections may slide toward and away from the centersection 296. The base member is formed With additional bent downportions 300, 301 beyond the extremities of the portions 297, 298,respectively, and these portions are coplanar in a plane slightly belowthe plane of portions 297, 298.

Immediately below the center section 296 and toward the rear of the tray20 is a disc 302 rotatably mounted as by a pivot pin 303. Similarly, asecond disc 304 is rotatably mounted as by a pivot pin 305 under theforward end of the tray. The discs 302, 304 are arranged so that theircenters are coincident With the longitudinal center line of the tray. Aconnecting link member 306 disposed between the center section 296 andthe discs 302 and 304 is pivotally connected at one end to the disc 302and at its other end to the disc 304 and in such a manner as to belongitudinally parallel to the longitudinal axis of the tray 20. Withthis arrangement, rotation of the disc 302 will produce correspondingrotation of the disc 304.

Pivotally mounted at one end to and below the disc 302 as by a pivot pin307 is a link member 308 which is pivotally connected at its other endby a pivot pin 310 to the lateral portion 294 of the left-hand anglemember 290. The pivot pin 310 extends through a slot 311 formed in thebent portion 300 of the base member 288 in order to connect the portion294 with the end of the link 308. Diametrically opposed to the pivot pin307 is a pivot pin 312 to which is pivotally connected a second linkmember 313 which has its other end pivotally con nected to the lateralportion 295 as by a pivot pin 314. The pivot pin 314 extends through aslot 315 formed in the bent portion 301 in order to make connection withthe link 313 which, as is the case for the link 308, is located belowthe disc 302. As viewed in FIG. 2, counterclockwise rotation of the disc302 will move the pivot pins 310, 314 closer together along a line thatgenerally includes the pivot pin 303. Conversely, clockwise rotation ofthe disc 302 will move the pins 310, 314 further apart, in each case thepins 310, 314 sliding within and being guided by the slots 311, 315,respectively.

At the forward end of the tray 20, or that end from which each sheet oftransfer material 287 is withdrawn during paper feed operation, the disc304 is provided with an identical linkage arrangement. Link members 316,317 are pivotally connected at one end by pins 318, 319, respectively,at diametrically opposed points on the disc 304 and at their other endsby pivot pins 321, 322 to the bent portions 300, 301, respectively.Slots 323, 324, formed in the bent portions 300, 301, accommodate therespective pins in-order to permit limited sliding movement of the pinsrelative to the respective bent portions.

In order to actuate the linkage thus far described, the rear disc 302 isprovided with a manually actuatable handle 325 which may be secured asby welding to the disc. Movement of the handle 325 in a counterclockwisedirection, as seen in FIG. 2, will similarly rotate the disc 302 aboutthe pivot 303. This action will move the pins 310, 314 toward eachother. Rotation of the disc 302 will also produce corresponding rotationof the disc 304 by means of the connecting link 306 and this action willmove the pins 321, 322 closer together. Movement of the pins 310, 321will be in unison and equal to the movement of the pins 314, 322. Theresultant action will draw the left and right upright guide portions292, 293 closer together in parallel and equal motion resulting incentering sheets of paper relative to their path of movement, regardlessof paper width.

During operation of the xerographic apparatus, a stack of transfermaterial sheets is placed in the tray 20 and the handle 325 manipulatedto bring the guides 292, 293 into contact with the adjacent edges of thesheets. This will insure that the stack is centrally located within thetray and in proper alignment with the paper feed rollers. In order toremove the stack, or to replace sheets, the handle 325 is rotated in aclockwise direction which results in the guides 292, 293 being movedaway from the stack, thereby clearing the same of impeding structure. Intheir movement toward or away from the stack of transfer material, theguides 292, 293 will slide with relative ease upon the bent portions297, 298, respectively. Their limit of travel in one direction will bedetermined by the engagement of the inner edges 326 of the portions 294,295 with the bent edges 327 of the central section 296 when there are nopaper sheets in the tray and will be determined by the guides 292, 293when sheets are present in the tray. The limit of travel in the otherdirection will be determined by the length of the Slots 311, 315, 323,324.

The tray 20 comprising the, base member 288, the guides 292, 293 and thelinkage arrangement is mounted for longitudinal movement as a unittoward and away from the feed rollers 280, 281. To this end, the basemember 288 is formed with up-turned flanges 328, 329 at each extremeside edge. These flanges extend beyond the guides 292, 293 and havesecured thereto the inner race 331 of a commercial type file cabinetdrawer slides. The outer races 332 for the slides are attached to asupport bracket 333 which extends across and beneath the entire tray 20and terminates beyond the side thereof into upstanding flanges 334, 335.Each of the outer races 332 is secured as by welding to the innersurface of the flanges 334, 335 and serve to support the tray 20 and thelinkage system relative to the support bracket 333. Suitableball-bearings mounted between the races 331 and 332 permit slidableaction between the tray 20 and the bracket 333 and removal of the trayfrom the apparatus. A spring latch 336 secured to the flange 335 bywelding has a bent end 337 engagable with the rear end of one of theinner races 331 which serves to detachably retain the tray in arelatively fixed position.

The tray 20 is also mounted for vertical movement and to this end thereis provided a left-hand support plate 338 secured to the frame plate 5by a bracket 340 and a right-hand support plate 341 secured to the frameplate 4 by a bracket 342. The support plates 338 and 341 are joinedtogether at their top portion by a connecting rod 343 and at their lowerportions by a support bar 344. Positioned between and secured to theflange 334 and the support plate 338 are the inner and outer races 345,346, respectively, of a file drawer slide 347 having suitable ballbearings between the races. Similarly, the flange 335 and the supportplate 341 have the inner and outer races of a cabinet slide 348 mountedtherebetween. Each of the slides 347, 348 extends vertically a distancethat will facilitate vertical movement of the tray 20 between its fullrange of movement while preventing rocking movement of the tray relativeto the fixed supporting structure for the tray.

The lower limit of movement of the tray is determined by a plurality ofstops 350 mounted on brackets 351 that are secured to the flanges 334,335. Preferably the stops 350 are located adjacent the four corners ofthe tray in order to prevent uneven settling of the tray and itsassociated parts.

In feeding sheets from the stack 287, one at a time, as the topmostsheet is advanced forward, the movement of the topmost sheet will tendto advance the second sheet also. In order to insure separation of thetopmost sheet only from the stack, there is provided at opposite cornersfrom the stack separating devices which apply a light restraining forceon the forward corners of the topmost sheet and the leading edge of thepaper stack. Each of the separating devices comprises a verticallymovable plunger 353, 354 freely movable in a tubular element 355, 356secured to the outside surface of upright portions 292 and 293,respectively, to be movable laterally therewith. Each of the plungers353, 354 has a snubber 357, 358 secured thereto to be movable there-WltlL. Since the separating devices are formed complementary to eachother, it is believed necessary to describe only one of the devices indetail. As shown in FIGS. 7, 8 and 9, the plunger 354 is formed with aradial slot 360 and within which is secured one leg 361 of a bentelement 362 upon which is secured the snubber 358. A slot 363 is formedaxially along the wall of the tubular element 356 and the leg 361extends through and is slidable within this slot which retains thesnubber 358 against rotation. With the plunger 358 being located on oneside of the paper stack 287, the snubber 358 is positioned against theleading edge of the stack with the snubber overlying the corner of thetopmost sheet. The elements 358, 361, 362 of the separating device arepreferably formed as a unitary structure stamped from sheet material.

The weight of each of the plungers 353, 354 is imposed on the upperforward corners of the paper stack and the weight on each corner is suchthat the plungers will follow the level of the stack downwardly as thestack level is lowered. Their weights also provide a restraining forcewhich will assist in the feeding of a single sheet of paper when thestack is acted upon by separator rollers to be described hereinafter.

As shown in FIG. 3, the lower ends of the plungers 353, 354 extendbeyond the depth of the stack 287 and terminate in rounded ends 364,preferably made from a plastic material such as Teflon. These ends areadapted to ride upon inclined plates 365 located below the plungers andthe outer edges 366 of the support bracket 333 on either side of thetray when the tray is moved rearwardly. As the tray 20 is retracted fromits paper feeding position, or to the left as shown in FIG. 3, theplungers 353, 354 will engage the inclined plates 365 and be raisedwhere they will remain as the tray is retracted. With the plungers heldin their uppermost position, the snubbers 357, 358 will be clear of thepaper stack thereby permitting the adding or removal of paper sheetsfrom the tray without encountering interference. Assuming that a newsupply of paper has been placed upon the tray and the same is moved toits forward position, the plungers will againresume their positions withthe snubbers resting upon the topmost sheet of the new supply.

To feed sheets of transfer material one at a time from the paper tray 20into the bite of the feed rollers 280, 281, there is provided a paperfeeding means comprising intermittently driven rollers 367 fixedlymounted upon a shaft 368 journaled in bearings 370 mounted in an arm 371adapted to swing about the axis of a shaft 372. The means for drivingthe rollers 367 comprises a pulley 373 secured to a conventional slipclutch 374, and a pulley 375 mounted on the shafts 368 and 372,respectively, and operatively connected together by means of timing belt376. The slip clutch 374 permits the rollers 367 to be rotated either bythe timing belt 376 or by frictional contact with a sheet of transfermaterial as it is pulled forward by the feed rollers 280 and 281.

The shaft 372 is journaled by a bearing 377 in the front plate 4, and bya bearing 378 in the arm 371 and, is normally biased to the left as seenin FIG. 10 by means of a spring 380 interposed between a snap ring 381on the shaft 372 and a shaft encircling washer 382 butted against theplate 4. As shaft 372 is forced to the left, the notched end of saidshaft is forced into the aperture in the end of a shaft SH3 to engagedrive pin secured therein. As shown in FIG. 11, the shaft SH3, which isjournaled in suitable bearings 384 positioned in the frame plate 215 anda sleeve 385 in the rear plate has an intermittently driven pulley 386secured thereon. A washer 387 rides against a shoulder on shaft SH3 toprevent outward axial movement of said shaft as viewed in FIG. 11.

To adjust the pressure of rollers 367 on the stack of transfer materialin paper tray 20, the arm 371 is fixed to one end of a hollow arm shaft388, the opposite end of the arm shaft being notched to engage locatingpins 390 secured to the counterbored end of the sleeve 385 journaled inthe plate 5, the sleeve being retained against axial movement to theright as seen in FIG. 3 by a snap ring 391 secured in a suitable grooveformed in the sleeve. The roller pressure on the stack of paper in papertray 20 due to gravity is suificient to maintain the sheets of paper inposition within the tray.

Interposed between rollers 367 and feed rollers 280 and 281 there isprovided, as shown in FIGS. 3 and 4, a pair of paper guides 392 and 393supported at opposite ends by the plates 4 and 5 to guide each sheet oftransfer material forwarded by rollers 367 into the bite of rollers 280and 281.

To permit the rollers 367 to clear a stack of copy sheets in the tray 20as the tray is moved to its normal operating position, as shown in FIG.(or when the tray is removed from its normal operating position), thereis provided a cam arm 394 secured to the sleeve 385 and a cam pin 395secured to the plate 5 for limiting the downward movement of the pivotarm 371 and the rollers 367. As will be described hereinafter, theheight of the paper stack 287 is maintained relatively constant, varyingonly by the thickness of a few sheets of paper. The cam pin 395 ispositioned such that if the tray 20 is retracted, the rollers will loweronly slightly and, upon movement of the tray to its normal paper feedposition, the rollers 367 will ride upward by its engagement withleading edges of the first few topmost sheets.

Forward progress of the tray movement up to its operating position isdetermined by a margin guide 396 which extends vertically from theforward portion 397 of the support bracket 333 to which it is secured.The guide 396 maintains the forward edges of the sheet of paper ingenerally vertical alignment and prevents inadvertent slippage of any orall the sheets. The height of the guide 396 is normally below that ofthe .snubbers 357, 358 which, as previously stated, rest upon thecorners of the topmost sheet of the stack 287, while the height of thesnubbers will vary somewhat by the thickness of a few sheets of paper.They will always occupy a position no lower than the upper edge of themargin guide 396 which must be cleared for a sheet of paper to be fed tothe feed rollers 280, 281.

In operation, as the topmost sheet is advanced by the rollers 367, theleading edge corners of the sheet engage the snubbers 357, 358 whereuponthe sheet will buckle upwardly and inwardly. As shown in FIGS. 2 and 9,the snubbers are tapered, being formed with an inner edge that is at anacute angle relative to the leading edges of the sheets of paper. As therollers 367 apply a forward force to the topmost sheet, the verticalportion of the elements 362 result in a lag in the forward movement ofthe corners as the sheet is continually advanced over the upper edge ofthe margin guide 362, this lag in cooperation with the angled inneredges of the snubbers will produce slight inward sliding movement of thecorners of the sheet of paper with consequent buckling of the sheet atits middle section. This buckling action of the topmost sheet insuresits separation from the underlying sheets in the stack.

As previously stated, the tray 20 is adapted for vertical movement inorder to maintain the plane or the level top of the stack 287 at arelatively fixed point. This is accomplished by the use of a motor driveand a .switching arrangement which will drive the tray 20 upwardly froman initial lower position when the tray supports a stack of paper to anuppermost position of the tray when only a few sheets of paper remain inthe tray.

This drive action is provided by a paper level drive motor M13 mountedfor sliding movement upon the stationary support bar 344. The motor M13is provided with a gear reduction device 400 and the output thereof istaken from the output shaft 401 to which is secured a drive gear 402.When the motor M13 is in its forward drive position, as shown in FIG. 3,the drive gear 402 is in mesh with a substantially larger driven gear403 secured intermediate the ends of a shaft 404 which extends below andtransversely of the tray 20, terminating in suitable bearings 405mounted in the fixed support plates 338, 341.

Secured to the ends of the transverse shaft 404, inwardly of the supportplates 338, 341, are gears 406, 407, each of which is in mesh with gearracks 408, 409, respectively. The rack 408 is secured to and dependsdownwardly from the outer surface of the flange 334 which, as waspreviously stated, is part of the support bracket 333. The rack 409 issecured to the other flange 335 of the bracket 333 and dependsdownwardly in the same manner. With the bracket 333 being movablevertically by means of the slides 347, 348, rotation of the gears 406,407 in a counterclockwise direction, as viewed in FIG. 3, will drive theracks vertically for moving the support bracket 333 upwardly. Thismovement will carry the tray 20 and, consequently, the stack 287therewith.

Preferably, the motor M13 is of the type which includes an internalbraking device which permits rotation of its output shaft 401 when themotor is energized, but locks the drive shaft against mechanicalrotation when the motor is deenergized. Energization of the motor M13 isunder control of a paper level limit switch 11LSB and a paper-low limitswitch 6LS. The limit switch 11LSB is mounted on the connecting rod 343which extends across the tray above the level of the stack 287 and isprovided with a depending paper level contacting finger 411 foractuating the switch into its open and closed positions. Normally, theswitch 11LSB is in its closed condition when no force is placed upon thefinger 411; however, when the level of the stack reaches a predeterminedheight, the top of the stack engages this finger to actuate the switch11LSB to its open condition.

As shown in the circuit diagram in FIG. 12, the switch 11LSB isconnected in series with the motor M13 and a suitable door interlockswitch 7LS, which is in closed condition when a door T to the basesection for the apparatus is closed. When the top of the stack 287 isbelow the predetermined level, the motor M13 will be energized until thetop of the stack reaches the predetermined level, whereupon the switch11LSB will be actuated to its open position for deenergizing the motor.Preferably, the gear reduction for the motor is such that the gears 406,407 will rotate approximately at the rate of 2 rpm. This slow speed willinsure proper orientation of the sheets of paper upon the tray duringmovement and sudden stopping thereof.

The limit switch 6LS is secured to the fixed support plate 338 andincludes an actuating arm 412 having a roller 413 thereon which isadapted to continuously engage one edge 414 of the gear rack 408. Theswitch 6L8 is normally closed when the rack 408 is in the position shownin FIG. 3, thus maintaining the circuit to a lowpaper relay SCR closed.For purposes of illustration, it will be assumed that the continuousxerographic printing cycle of the xerographic apparatus is dependentupon the closed condition of a normal-1y closed switch SCR-1 and thatthe program arrangement for the electrical circuit for the apparatus issuch that if the switch 5CR-1 is opened, printing by the apparatus willterminate, which occurs when the relay SCR is deenergized.Deenergization will occur when the limit switch 6LS is actuated to itsopen position.

As the tray is moved upwardly when paper is being fed out of the tray 20under the power produced by the motor M13 and as controlled by the leveldetermining switch 11LSB, the roller 413 on the actuator arm for thepaper-low switch 6LS approaches a detent 415 formed at the lowermostpoint of the gear rack 408. This occurs as the paper stack becomesgradually depleted through use of the xerogra-phic apparatus. When thepaper tray 20 contains only a few sheets of paper, the roller 413 willroll into the detent 415 causing actuation of the switch 6LS to its openposition which, in turn, will open the circuit to the relay SCR andpermit opening of the switch SCR-1. With the printing apparatus shutdown, the operation of the xerographic apparatus terminates until paperis added to the tray 20 in order to cause closing of the paper-lowswitch 6LS.

As previously stated, the motor M13 is provided with an internal brakingdevice which, when the tray 20 is in its paper-low, uppermost positionto produce opening of the switch 6L8, will prevent mechanical reversalof the motor when deenergized and thus prevent lowering of the trayunder the weight of a new stack of sheet material or under any loadingcondition. In order to produce lowering of the tray 20 for permitting anoperator to add paper, the paper feed mechanism also includes amechanical interlock device between the door T to the printing apparatusand the tray drive motor M13.

This mechanical interlock device is associated with the paper leveldrive motor M13 and is arranged to physically move the motor into or outof engagement with the gear system for the tray raising function. Asshown in FIG. 6, the motor is mounted by a bracket 416 to the upperinner race 417 of a drawer slide, having a lower outer race 418 securedto the support bracket 344. The bracket 416 also has secured thereto byvertically positioned bolts 420, the bite portion of a U-shaped member421, the legs of which extend downwardly to straddle the slide races417, 418 as well as the bracket 344. The member 421 is formed with alateral extending tongue 422 having secured thereto one end of a coilspring 423 which has its other end secured to a post 424 on the bracket344. The spring 423 serves to bias the member 421 to the left, as viewedin FIG. 5, and thereby to force the motor M13 and its output drive gear402 in that same direction. Adjusting screws 425, 426 mounted on thelegs of the member 421 and enga-gable with the edges of the bracket 344set the limit of movement for the motor in either direction.

Normally, the motor M13 is biased to the left until the front adjustingscrew 426 is against the adjacent edge of the bracket 344. This actionwill result in movement of the drive gear 402 to the left to becomedisengaged from the gear 403 whereupon the tray 20 will lower by gravityuntil the support plate 333 comes to a stop upon the stops 350. In orderto maintain the drive gear 402 in mesh with the gear 403, there isprovided a door-engaging actuator 427 secured by the bolts 420 to theupper race 417 for actuating the elements 417, 421, 416 and the motorM13 to the right when the apparatus cabinet door T is in a closedposition. This is accomplished by the provision of a push rod 428 at theouter end of the actuator for direct engagement with the door whenclosed. A coil spring 429 is held within the actuator 427 and serves toforce the rod 428 outwardly and to act as an override mechanism in theevent that the extreme tips of the teeth of the gear 402 impinge uponthe extreme tips of the gear teeth of gear 403. Upon this occurrence,assuming that the door T has been closed, the coil spring 429 will becompressed in order to relieve the mechanical strain upon the rod 427.In the event that there is direct engagement of the gear teeth, anyattempt to raise the tray for elevating the stack by rotating the gear402 will produce meshing with the gear 403 under the force produced bythe spring 429. With the spring 429 being stronger than the spring 423,the bracket 416 will be forced to the right against the force producedby the spring 423 in order to permit proper meshing of the gears 402 and403.

With the gears in mesh and the llimit switch 11LSB closed because of thelowermost position of the paper stack 287, the motor M13 will becomeenergized to raise the tray to pass the position it occupied justprevious to the time the door T was opened. The mechanical interlockdevice, as understood from the foregoing description, is operable tolower the tray 20 whenever the operator opens the door T. Generally,this is necessary only when paper is to be added to the tray and theensuing lowering of the tray 20 conditions the same for the addition ofpaper. The operator need only retract the tray toward the door T topermit actuation of the plungers 353, 354 upwardly out of the way of theremaining paper stack or the completely empty tray. In this arrangement,the chance that the operator will load the tray when the same is not inproper condition, is eliminated.

Both the operation of the paper separator rolls 367 and the paper feedroll 280 is effected by a clutch mechanism 430 having separate clutchdrives, the selection of the drives being controlled by means of aduplex clutch shifting armature actuated by a programmer to be discussedhereinafter.

As illustrated in FIG. 11, the clutch mechanism 430, which is supportedand housed by the frame plates 5 and 215, includes a horizontal drivenshaft SH4 that rotates at one end by means of .a pin 431 mounted by ascrew in frame plate 5, the end of the shaft being formed with a cavityto receive the end of the pin 431. A thrust washer 432 encircles theshaft on the inside of the plate 5. At its opposite end, the shaft SH4is journaled in a bearing 433 mounted in the frame plate 215.

The clutch mechanism includes two complementary magnet assemblies 434and 435 which are free to rotate relative to the shaft. A third clutchelement 436, which in effect is an armature and adapted to coact withcomplementary magnet assemblies 434 and 435, is fitted on shaft SH4 ininterposed relation to the magnet assemblies and is free for relativemovement with respect to the axis of the shaft SH4. However, thearmature is connected to the shaft for rotation therewith by means of aseries of flexible metallic diaphragms 437 secured along theirperipheries to an internal wall of the central por tion of the armatureand at their center points to an armature hub 438, which in turn is heldin place on the shaft SH4 by a key 439. A spacing 440 is provided onboth sides of the armature and the adjacent side wall of each clutchelement 434, 435 to permit limited sliding movement of the armaturealong the shaft in either direction. The armature 436 is provided withfriction pads 441 on both sides there-of to be engagable with eithermagnet assembly 434 or 435, depending upon which of these assemblies iselectrically energized.

The frictional surfaces of the armature 436 are spaced a distanceslightly smaller than the spacing 440 from the opposed surface of themagnet assemblies to permit axial movement of the armature whereby itmay be selectively engaged with either magnet assembly. When eithermagnet assembly is energized, magnetic flux flows from that assemblyinto the armature and attracts the armature to that assembly. Theensuing axial movement of the armature is accomplished by deflection ofthe flexible diaphragm 437 since the hub 438 is fixed on the shaft. Thetorque developed on the shaft SH4 is transmitted by the armature hub438, which rotates with the shaft to the flexible diaphragm and byfriction from the friction facings 441 to the assembly 434. The magnetassembly 434 is, in effect, a driving element and is secured to a pulley442 which in turn serves to drive the pulley 386 by a timing belt 443for driving the paper feed rollers 367. In a similar manner, the magnetassembly 435 is in effect a driven element secured to a pulley 444adapted to be connected by timing belt 445 to driven pulley 284 mountedon the shaft SH6 to drive the paper register roller 280.

In order to impart rotation to the shaft SH4 to effect rotation ofeither the paper feed roller drive shaft SH3 or the paper registerroller drive shaft SH6, the shaft SH4 has secured thereto a drivenpulley 446 connected to a pulley 447 secured to the drum drive shaft SH7by a timing belt 448 which also encircles an idler pulley 450 rotatableon shaft SH9. A suitable drive mechanism including a motor (not shown)may be utilized to drive the drum 14 and the paper feed mechanism aspart of the main drive system for the xerographic apparatus. Such adrive mechanism may include a pulley 485 mounted on a shaft SH11 andconnected to a main motor and a pair of pulleys 486, 487 mounted on theshafts SH11, SH7, respectively, for driving the drum 14. With thisarrangement, the shaft SH4 is continually rotated along with the drum 14while the machine is in operation.

The magnet assemblies 434 and 435 are each provided with a pair ofcommutator rings 451 and 452, respectively, which are adapted tocontinuously engage suitable brushes 453 and 454. The brushes are partof the electrical circuit for the machine and, as shown in FIG. 12, thebrushes 453 connect the coil of the magnet assembly 434, illustrated asa solenoid SOL1, across the output terminals of a DC. rectifier SR3while the brushes 454 connect the coil of the magnet assembly 435,illustrated as a solenoid SOL-7, across the output terminals of the DC.rectifier SR4.

Energization of either the magnet assembly 434 or the magnet assembly435 is under control of a rotatable cam 455 secured on the shaft SH4, asshown in FIG. 12. The periphery of the cam 455 is formed with a cam lobe456 which periodically engages and actuates a cam follower 457 mountedto a frame structure 458 secured on the rear frame plate 215. Whenactuated, the cam follower 457 in turn actuates a paper feed limitswitch 17LS, also mounted on the frame structure 458 and comprising twoswitches 17LSA and 17LSB, one of which will close while the other opensduring actuation of the switch 17LS. As shown in FIG. 12, the switch17LSB is normally closed so that the register roller 280 is normallyrotating while the cam 455 is rotating out of engagement with thefollower 547. During this cycle of operation, the switch 17LSA is openand the magnet assembly 434 is deenergized. When the lobe 456 is rotatedaround to engage the follower 457, the switch 17LSB is opened and theswitch 17LSA closed. Opening of switch 17LSB will cause deenerigzationof the magnet assembly 435 which releases the armature 436 therefrom toterminate the drive connection to the register roller. Closing of theswitch 17LSA will produce energization of the magnet assembly 434resulting in the attraction thereto of the armature for producing adrive connection between the shaft SH4 and the feed roller shaft SH3.

Referring back to the operation of the paper feed rollers 367 and thepaper register rollers 280 and 28 1, when the paper feed rollers 367 aredriven by the energized magnetic assembly 434, the magnet assembly 435for driving the roller 280 is deenergized since at this stage of theoperation, the switch 17LSA is closed. As the rollers 367 are driven,they forward a sheet of transfer material into the bite of rollers 280and 281 where its forward motion is momentarily stopped. As the movementof a sheet of transfer material under the rollers 367 continues afterthe leading edge of the sheet has been stopped by rollers 280 and 281,the sheet is buckled as the rollers continue to rotate. The rotation ofrollers 367 is continued just sufliciently to bow the paper whereby theresiliency of the paper forces the leading edge of the sheet intotransverse alignment with the rollers 280 and 281, irrespective of itsoriginal alignment thereto, so that the paper is forwarded by saidrollers in correct alignment with the drum 14 as the roller 280 isactivated by movement of the cam lobe 456 to close the switch 17LSB,permitting the armature 436 to become magnetically coupled to the magnetassembly 434.

While the invention has been described with reference to the structuresdisclosed herein, it is not confined to the details set forth and thisapplication is intended to cover such modifications or changes as maycome within the purpose of the improvements or the scope of thefollowing claims.

What is claimed is:

1. A paper level control system for a paper feed mechanism including aframe,

a tray for supporting a stack of sheets mounted in said frame forvertical movement,

a gear rack mounted on said tray and movable therewith,

a motor and a gear driven by said motor and operatively engageable withsaid gear rack, said motor being adapted to drive said tray upwardlywhen the same is energized,

means for supporting said motor for movement relative to said tray fordisrupting the operative engagement of said gear from said gear rack,

an electrical circuit connected to said motor and to a source ofelectric power,

first and second switching means connected in said circuit forcontrolling energization of said motor,

feelcr means associated with said first switching means for actuatingthe same and being adapted to co act with the top of the stack of sheetsat a predetermined plane,

said first switching means being normally held in one of its controllingpositions for energizing said motor and actuatable to its othercontrolling positions to 'deenergize said motor when the top of thestack reaches said predetermined plane,

means for producing movement of said motor for disrupting the operativeengagement of said gear with said gear rack and for producing actuationof said second switching means into its open position whereby the traywill lower while said motor is deenergized.

2. A paper level control system for a paper feed mechanism including aframe,

a tray for supporting a stack of sheets mounted in said frame forvertical movement,

a gear rack mounted on said tray and movable therewith,

a motor and a gear driven by said motor and operatively engageable withsaid gear rack for supporting the tray against the force of gravity,said motor being adapted to drive said tray upwardly when the same isenergized,

means for supporting said motor for movement relative to said tray fordisrupting the operative engagement of said gear from said gear rack,

an electrical circuit connected to said motor and to a source ofelectric power,

first ond second switching means connected in series in said circuit forcontrolling energization of said mot-or,

feeler means associated with said first switching means foractuatingjthe same and being adapted to co-act with the top of the stackof sheets at a predetermined plane, it

said first and second switching means being normally held in a closedcondition for energizing said motor said first switching means beingactuatable to its 14 open condition to deenergize said motor when thetop of the stack reaches said predetermined plane, means for producingmovement of said motor for disrupting the operative engagement of saidgear with said gear rack and cause lowering of the tray due to gravityand for producing actuation of said second switching means into its opencondition whereby said motor will be deenergized.

References Cited by the Examiner UNITED STATES PATENTS 1,065,085 6/1913Steere 27162 1,349,133 8/ 1920 Hulbert 271-62 2,922,544 1/ 1960Perzentka 271-39 2,999,686 9/1961 Cheeseman et a1. 27162 X ROBERT B.REEVES, Primary Examiner.

20 F. R. HANDREN, Assistant Examiner.

1. A PAPER LEVEL CONTROL SYSTEM FOR A PAPER FEED MECHANISM INCLUDING AFRAME, A TRAY FOR SUPPORTING A STACK OF SHEETS MOUNTED IN SAID FRAME FORVERTICAL MOVEMENT, A GEAR RACK MOUNTED ON SAID TRAY AND MOVABLETHEREWITH, A MOTOR AND A GEAR DRIVEN BY SAID MOTOR AND OPERATIVELYENGAGEABLE WITH SAID GEAR RACK, SAID MOTOR BEING ADAPTED TO DRIVE SAIDTRAY UPWARDLY WHEN THE SAME IS ENERGIZED, MEANS FOR SUPPORTING SAIDMOTOR FOR MOVEMENT RELATIVE TO SAID TRAY FOR DISRUPTING THE OPERATIVEENGAGEMENT OF SAID GEAR FROM SAID GEAR RACK, AN ELECTRICAL CIRCUITCONNECTED TO SAID MOTOR AND TO A SOURCE OF ELECTRIC POWER, FIRST ANDSECOND SWITCHING MEANS CONNECTED IN SAID CIRCUIT FOR CONTROLLINGENERGIZATION OF SAID MOTOR, FEELER MEANS ASSOCIATED WITH SAID FIRSTSWITCHING MEANS FOR ACTUATING THE SAME AND BEING ADAPTED TO CO-ACT WITHTHE TOP OF THE STACK OF SHEETS AT A PREDETERMINED PLANE, SAID FIRSTSWITCHING MEANS BEING NORMALLY HELD IN ONE OF ITS CONTROLLING POSITIONSFOR ENERGIZING SAID MOTOR AND ACTUATABLE TO ITS OTHER CONTROLLINGPOSITIONS TO DEENERGIZE SAID MOTOR WHEN THE TOP OF THE STACK REACHESSAID PREDETERMINED PLANE, MEANS FOR PRODUCING MOVEMENT OF SAID MOTOR FORDISRUPTING THE OPERATIVE ENGAGEMENT OF SAID GEAR WITH SAID GEAR RACK ANDFOR PRODUCING ACTUATION OF SAID SECOND SWITCHING MEANS INTO ITS OPENPOSITION WHEREBY THE TRAY WILL LOWER WHILE SAID MOTOR IS DEENERGIZED.